"In many respects, he spoiled us. When you progress on a flat line, outside observers are lulled into the tacit expectation that this is how it's supposed to be. Players like this produce so deceptively that we miss the escalating work ethic required to stave off age, the sheer dominating focus it takes to be so steady at such a high level."

If you're a tennis fan, the above graph has to make you think of Roger Federer. He turns 30 next month. That's an ominous birthday for a professional tennis player. Pete Sampras was grinding through what would be a two-year slump (before he went out in a blaze of glory). Jim Courier and Marat Safin had already stumbled, loss after dispiriting loss, into retirement. John McEnroe was more than four years removed from his final major singles title. Boris Becker had fallen out of the Top 50.

Federer is at No. 3 in the world and holding steady. He is the defending World Tour Final champion and just reached the French Open final. Players in the Open Era who have remained at the top of the game at 30 make up a very short list: Rod Laver, Ken Rosewall, Jimmy Connors, Andre Agassi. All of them are all-time greats.

Federer's longevity -- at present solidly entrenched among the best but not quite the best of the best -- also leads us to forget just how dominant he was in his prime. After his loss to Jo-Wilfried Tsonga at Wimbledon, Federer reacted with understandable annoyance when asked about his middling career five-set record (16-13): "When I was probably losing four matches a year I wasn't even in fifth sets."

This has been the whispering about Federer ever since his back-to-back five-set losses to Rafael Nadal in the 2008 Wimbledon final and the 2009 Australian Open final. He's fabulously talented, goes the theory, but he doesn't have the guts, the will, of other great champions.

How quickly conventional wisdom changes. Before Nadal reached his prime and Federer began to slip ever so slightly from his peak form, it was widely acknowledged that for all his physical gifts, Federer's greatest weapon was his will to win and his ability to perform best when it mattered most.

Below is an ESPN "Outside the Lines" segment from 2005 featuring Laver and Tennis Channel founder Steve Bellamy. At the time of the show, Federer had just secured his third straight Wimbledon title and had won 22 straight tournament finals. "To come off and win like 20 finals in a row, to win on all surfaces, it's quite incredible," Laver said. The two-time calendar-year Grand Slam champ added: "The main thing is, he just plays well under pressure, and that's the thing that takes him apart from all the other players."

This leads me to another thought. We talk a fair amount about how guys like Andre Agassi and Boris Becker and even McEnroe didn't fulfill their potential -- at least not in a sustained way over their careers. But what about the guys who managed to win multiple Slams even though they weren't the most talented or athletically gifted of their era? We rarely talk about the Pete Roses of tennis. My top three:

1. Mats Wilander. Here's a guy who wouldn't have minded being wrongly convicted of murder, because then he would have been guaranteed 20 glorious, sun-dappled years on a chain gang breaking big rocks into smaller rocks. Despite one-note athleticism and a dearth of imagination, he won seven major singles titles, including three in 1988.

2. Jim Courier. Watch him now on the seniors tour. He looks like a club player: Big-ish forehand, crappy backhand slice, no net game. And not particularly fleet of foot. How did he win four major titles? Hard work and determination. (That's also why he burned out and fell down to the rankings' middle rungs almost as quickly as he had risen to the top.)

3. Guillermo Vilas. A dashing poet off the court, a plodding grinder on the court. He was heavy-legged compared to Vitas Gerulaitis, unimaginative compared to Adriano Panatta -- and yet he won four major singles titles, compared to a combined two by contemporaries Gerulaitis and Panatta.

Honorable mention: Jan Kodes, French Open champion in 1970 and '71 -- and winner of the strike-weakened 1973 Wimbledon.